Hi all,
i was watching some train technology when i saw this video:
someone had the brilliant idea to use inductor for recording VFD sounds.
https://www.youtube.com/watch?v=8izkZyDm9R8

It is really interesting about those sounds which can't be heared as this otherwise.

The trains with gate turn-off thyristors (GTOs) usually sound the coolest when they are accelarating and decelerating. This has sometimes given them the nickname "singing trains".
GTO inverters were most notably used in the Amtrak Acela Express, LA Metro Rail A650, Toronto Subway T1, the Washington Metro 1000 series, and the London Underground 1996 stock.

Yeah the T1 trains used here have pretty interesting, acceleration, deceleration and braking sounds. The newer TR trains used here are IGBT are sound fairly mundane. IIRC the T1 also used Westinghouse/AEG propulsion for the traction system. Also apparently there's a IGBT "retrofit" inverter on the T1. I don't think it's documented online but I saw a IGBT retrofitted inverter tray on display the last time the yard had an open house.

The now decommissioned trains that preceded the T1, the H5 and H5 used GTO chopper technology with DC traction motors and those had a pretty unique sound signature too. Same goes for the ICTS trains used in Toronto and also still used in the Vancouver and Detroit systems, IIRC those had GTO inverters too, but drove a linear induction motor.

Do you know of any way I can identify what kind of DC chopper control (normal thyristor or GTO thyristor) a train uses based on how it sounds?

The classic SCR (non GTO thuyristor) regulators are even better - usually the commutation inductor (used to create pulses to turn the main thyristor off) uses to be very "singy". Plus these use to be operating at way slower frequencies than the GTO or even IGBT ones...

When I was in NYC 10 years ago, I remember being fascinated by the unique sounds that the various models of Subway cars made.  The older DC operated cars were pretty boring, except for the R62/R68 cars, who's air brake systems earned them the name "Darth Vader trains".  The AC operated cars had very distinct sounds, depending on the model of drive inverter they used.  Most of my rides were on Alstom powered R160 trains, but sometimes I'd end up on a Siemens powered R160 train.  The most unique sounding was the R142A and R143 trains powered by Bombardier inverters.